Economical improvement on the performances of a soybean flour-based adhesive for wood composites via montmorillonite hybridization

Abstract Bond performance and cost are key factors that significantly affect the commercial utilization of soybean-based adhesives in wood composites. A desired soybean-based adhesives with reduced adhesive cost and improved bond performance and technological applicability was developed in this study by organic-inorganic hybridization through combining montmorillonite clay (MMC) with thermochemically modified soybean flour (TMSF) for better crosslinking efficiency. The results showed that the species of inorganic filler and the level of MMC as filler had important effects on the performance of the modified adhesive. The soybean-based adhesive with 20% MMC addition achieved a 9.0% decrease of adhesive cost along with a 24.5% increase in weather resistance and improved technological applicability (in terms of the decreased viscosity and alleviated shear thinning phenomenon), which was suitable for producing outdoor-use plywood. The improved water resistance of the TMSF-based adhesive was attributed to the reinforcement from the organic-inorganic hybridization of adhesive of partially intercalated MMC, the good dispersion of MMC particles in adhesive and the better crosslinking efficiency of TMSF to crosslinker than native soybean flour. Thus, this novel strategy could effectively expand the applications of TMSF-based adhesives in environmentally friendly wood composites.